Method for estimating a friction coefficient

Abstract

A method and a system for estimating a friction coefficient between a driven wheel and a surface. The method uses a Fourier series to calculate the friction coefficient. More specifically, a desired wheel slip ratio is calculated using received sensor readings related to a system state and a desired wheel speed determined from various system conditions or user inputs. A Fourier series is used to estimate the friction coefficient. The method is generally cycled many times each second to allow for varying road conditions by adjusting the Fourier series coefficients after each cycle. The system generally includes a wheel speed sensor and an accelerometer providing signals to a processor or various modules to perform the above method.

Description

BACKGROUND OF THE INVENTION The present invention relates generally to a method of estimating a friction coefficient between a driven wheel and a surface and more specifically to a method of estimating the longitudinal friction force coefficient between a driven wheel and a surface. The estimation of a friction coefficient between a driven wheel and a surface is important for a wide variety of applications including vehicle traction and stability control systems. These systems estimate the friction coefficient of a driven wheel to improve traction and handling characteristics of the vehicle. One problem with the current methods for estimating a friction coefficient is the difficulty in providing real time on-line estimation of the friction coefficient. Typically current methods rely on processing large amounts of past accumulated data and cannot be expected to quickly adapt to changes. Another problem with these methods is the amount of memory and computing power necessary to proc...

AI Technical Summary

Benefits of technology

The present invention uses a Fourier series to calculate a friction coefficient between a driven wheel and a surface. More specifically, a plurality of sensors provide data indicative of a system state to a processor which determines an estimated wheel speed, selects a desired wheel speed, and calculates a desired wheel slip ratio. A Fourier series is then us

Problems solved by technology

One problem with the current methods for estimating a friction coefficient is the difficulty in providing real time on-line estimation of the friction coefficient.

Typically current methods rely on processing large amounts of past accumulated data and cannot be expected to quickly adapt to changes.

Another problem with these methods is the amount of memory and computing power necessary to process the accumulated data.

These problems are particularly acute for vehicles in which real time data regarding the friction coefficient is necessary to allow control systems to quickly respond to changing road conditions.

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